We are pursuing an in-depth investigation on the structure and function of the membrane receptor for immunoglobulin E (IgE). The principal cells with which we are working is a line of rat basophilic leukemia cells which can be grown in vivo as solid tumors or in vitro. During the past year we have pursued the following studies: 1) an evaluation of those conditions that promote or inhibit the dissociation of the subunits of the receptors, 2) further characterization of the subunits, 3) development of probes to identify the genes of the receptors, 4) induction of monoclonal antibodies to the subunits of the receptors, 5) studies on the putative ion channels induced as an early stage of activation of the receptors, 6) the role of phosphatidyl inositol turnover as an early receptor-initiated event.